SQLite

Check-in [1330c72e17]
Login

Many hyperlinks are disabled.
Use anonymous login to enable hyperlinks.

Overview
Comment:Simplification to the random rowid picking logic that begins running when the maximum possible rowid has already been used.
Downloads: Tarball | ZIP archive
Timelines: family | ancestors | descendants | both | trunk
Files: files | file ages | folders
SHA1: 1330c72e172324c68ab49e5bb2ceba985935ae01
User & Date: drh 2014-09-25 12:31:28.476
Context
2014-09-25
13:17
Simplifications to the SQL function and aggregate calling procedures. (check-in: 3467049a17 user: drh tags: trunk)
12:31
Simplification to the random rowid picking logic that begins running when the maximum possible rowid has already been used. (check-in: 1330c72e17 user: drh tags: trunk)
11:08
Still more performance enhancements to the LIKE and GLOB operators. (check-in: 6c8924cacc user: drh tags: trunk)
Changes
Unified Diff Ignore Whitespace Patch
Changes to src/vdbe.c.
4016
4017
4018
4019
4020
4021
4022
4023
4024


4025
4026
4027
4028
4029
4030
4031
4032
4033
4034
4035
4036
4037
4038
4039
4040
4041
4042
4043
4044
4045
4046
4047
4048
    if( pC->useRandomRowid ){
      /* IMPLEMENTATION-OF: R-07677-41881 If the largest ROWID is equal to the
      ** largest possible integer (9223372036854775807) then the database
      ** engine starts picking positive candidate ROWIDs at random until
      ** it finds one that is not previously used. */
      assert( pOp->p3==0 );  /* We cannot be in random rowid mode if this is
                             ** an AUTOINCREMENT table. */
      /* on the first attempt, simply do one more than previous */
      v = lastRowid;


      v &= (MAX_ROWID>>1); /* ensure doesn't go negative */
      v++; /* ensure non-zero */
      cnt = 0;
      while(   ((rc = sqlite3BtreeMovetoUnpacked(pC->pCursor, 0, (u64)v,
                                                 0, &res))==SQLITE_OK)
            && (res==0)
            && (++cnt<100)){
        /* collision - try another random rowid */
        sqlite3_randomness(sizeof(v), &v);
        if( cnt<5 ){
          /* try "small" random rowids for the initial attempts */
          v &= 0xffffff;
        }else{
          v &= (MAX_ROWID>>1); /* ensure doesn't go negative */
        }
        v++; /* ensure non-zero */
      }
      if( rc==SQLITE_OK && res==0 ){
        rc = SQLITE_FULL;   /* IMP: R-38219-53002 */
        goto abort_due_to_error;
      }
      assert( v>0 );  /* EV: R-40812-03570 */
    }
    pC->rowidIsValid = 0;







<
|
>
>
|
|
<
|


|
<
<
<
<
<
<
<
<
<
<







4016
4017
4018
4019
4020
4021
4022

4023
4024
4025
4026
4027

4028
4029
4030
4031










4032
4033
4034
4035
4036
4037
4038
    if( pC->useRandomRowid ){
      /* IMPLEMENTATION-OF: R-07677-41881 If the largest ROWID is equal to the
      ** largest possible integer (9223372036854775807) then the database
      ** engine starts picking positive candidate ROWIDs at random until
      ** it finds one that is not previously used. */
      assert( pOp->p3==0 );  /* We cannot be in random rowid mode if this is
                             ** an AUTOINCREMENT table. */

      cnt = 0;
      do{
        sqlite3_randomness(sizeof(v), &v);
        v &= (MAX_ROWID>>1);
        v++;

      }while(  ((rc = sqlite3BtreeMovetoUnpacked(pC->pCursor, 0, (u64)v,
                                                 0, &res))==SQLITE_OK)
            && (res==0)
            && (++cnt<100));










      if( rc==SQLITE_OK && res==0 ){
        rc = SQLITE_FULL;   /* IMP: R-38219-53002 */
        goto abort_due_to_error;
      }
      assert( v>0 );  /* EV: R-40812-03570 */
    }
    pC->rowidIsValid = 0;
Changes to test/rowid.test.
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
} {a}
do_test rowid-12.2 {
  db close
  sqlite3 db test.db
  save_prng_state
  execsql {
    INSERT INTO t7 VALUES(NULL,'b');
    SELECT x, y FROM t7;
  }
} {1 b 9223372036854775807 a}
execsql {INSERT INTO t7 VALUES(2,'y');}
for {set i 1} {$i<100} {incr i} {
  do_test rowid-12.3.$i {
    db eval {DELETE FROM t7temp; INSERT INTO t7temp VALUES(1);}
    restore_prng_state
    execsql {
      INSERT INTO t7 VALUES(NULL,'x');







|

|







675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
} {a}
do_test rowid-12.2 {
  db close
  sqlite3 db test.db
  save_prng_state
  execsql {
    INSERT INTO t7 VALUES(NULL,'b');
    SELECT x, y FROM t7 ORDER BY x;
  }
} {/\d+ b 9223372036854775807 a/}
execsql {INSERT INTO t7 VALUES(2,'y');}
for {set i 1} {$i<100} {incr i} {
  do_test rowid-12.3.$i {
    db eval {DELETE FROM t7temp; INSERT INTO t7temp VALUES(1);}
    restore_prng_state
    execsql {
      INSERT INTO t7 VALUES(NULL,'x');